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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
5.1 Light and Quantized Energy
Objectives
• Compare the wave and particle natures of light.
• Define a quantum of energy, and explain how it is related to an energy change of
matter.
• Contrast continuous electromagnetic spectra and atomic emission spectra.
Main Idea: ________, a form of electromagnetic radiation, has characteristics of both a
_______ and a _____________.
The Atom and Unanswered Questions
• Recall that in Rutherford's model, the atom’s _________ is concentrated in the
______________, and _______________ move around it.
• The model doesn’t explain how the electrons were __________ around the nucleus.
• The model doesn’t explain why ____________ charged electrons aren’t
_____________ into the _____________ charged nucleus.
• Analysis of the _____________ light revealed that an element’s ____________
behavior is related to the __________________ of the electrons in its atoms.
The Wave Nature of Light
• Visible light is a type of ____________________ _______________, a form of
energy that exhibits ____________-like behavior as it travels through space.
• ____________ waves can be described by several characteristics.
• The ________________ (λ) is the shortest distance between equivalent points on
a continuous wave.
• The ________________ (ν) is the number of waves that pass a given point per
second.
• The ________________ is the wave’s height from the origin to a crest.
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The ________________ (3.00  108 m/s) is the product of its wavelength and
frequency.
c = λν
c = speed of light
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Honors Chemistry
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Chapter 5 Electrons in Atoms
Notes Outline
________________ contains a continuous range of wavelengths and frequencies.
A ________________ separates sunlight into a continuous spectrum of colors.
The ________________ ________________ includes all forms of
electromagnetic radiation.
Example Problem 1 Calculating Wavelength of an EM wave Microwaves are used to cook
food and transmit information. What is the wavelength of a microwave that has a
frequency of 3.44 x 109 Hz?
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
Practice Problems (page 140)
1. Objects get their colors from reflecting only certain wavelengths when hit with
white light. Light reflected from a green leaf is found to have a wavelength of 4.90
x 10-7 m. What is the frequency of the light?
2. X-rays can penetrate body tissues and are widely used to diagnose and treat
disorders of internal body structures. What is the frequency of an x-ray with a
wavelength of 1.15 x 10-10 m?
3. After careful analysis, an electromagnetic wave is found to have a frequency of 7.8
x 106 Hz. What is the speed of the wave?
4. Challenge While an FM radio station broadcasts at a frequency of 94.7 MHz, an AM
station broadcasts at a frequency of 820 kHz. What are the wavelengths of the two
broadcasts? Which of the drawings below corresponds to the FM station? To the
AM station?
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
The Particle Nature of Light
• The _____________ model of light cannot explain all of light’s characteristics.
• Matter can gain or lose energy only in small, specific amounts called ____________.
• A ________________ is the minimum amount of energy that can be gained or lost
by an atom.
• ________________ ________________ has a value of 6.626  10–34 J ● s.
• The ________________ ________________ is when electrons are emitted from
a metal’s surface when light of a certain frequency shines on it.
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________________ ________________ proposed in 1905 that light has a
_____________ nature.
A beam of light has ________________ and ________________ properties.
A ________________ is a particle of electromagnetic radiation with no mass that
carries a quantum of energy.
Ephoton = h
E
photon
represents energy.
h is Planck's constant (6.626  10–34 J ● s).
 represents frequency.
Example Problem 2 Calculate the Energy of a Photon Every object gets its color by
reflecting a certain portion of incident light. The color is determined by the wavelength of
the reflected photons, thus by their energy. What is the energy of a photon from the
violet portion of sunlight if it has a frequency of 7.230 x 1014 s-1?
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
Practice Problems (page 143)
5. Calculate the energy possessed by a single photon of each of the following types of
electromagnetic radiation.
a. 6.32 x 1020 s-1
b. 9.50 x 1013 Hz
c. 1.05 x 1016 s-1
6. The blue color in some fireworks occurs when copper(I) chloride is heated to
approximately 1500 K and emits blue light of wavelength 4.50 x 102 nm. How much
energy does one photon of this light carry?
7. Challenge The microwaves used to heat food have a wavelength of 0.125 m. What is
the energy of one photon of the microwave radiation?
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
Atomic Emission Spectra
• Light in a neon sign is produced when ________________ is passed through a tube
filled with neon gas and ________________ the neon atoms.
• The excited atoms emit light to ________________ energy.
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The ________________ ________________ ________________ of an element
is the set of frequencies of the electromagnetic waves emitted by the atoms of the
element.
Each element’s atomic emission spectrum is ________________.
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
5.2 Quantum Theory and the Atom
Objectives
• Compare the Bohr and quantum mechanical models of the atom.
• Explain the impact of de Broglie's wave article duality and the Heisenberg
uncertainty principle on the current view of electrons in atoms.
• Identify the relationships among a hydrogen atom's energy levels, sublevels, and
atomic orbitals.
Main Idea: ________________ properties of electrons help relate atomic emission
spectra, energy states of atoms, and atomic orbitals.
Bohr’s Model of the Atom
• Niels Bohr correctly ________________ the frequency lines in ________________
atomic emission spectrum.
• The lowest allowable energy state of an atom is called its ________________
________________.
• When an atom ________________ energy, it is in an excited state.
• Bohr suggested that an electron moves around the nucleus only in certain allowed
circular ________________.
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Each orbit was given a number, called the ______________ ______________.
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Honors Chemistry
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Chapter 5 Electrons in Atoms
Notes Outline
Hydrogen’s single electron is in the ________________ orbit in the ground state.
When energy is added, the electron moves to the ________________ orbit.
Bohr’s model explained the hydrogen’s spectral lines, but failed to explain any
________________ element’s lines.
The ________________ of electrons is still not fully understood, but it is known
they ________________ move around the nucleus in circular orbits.
The Quantum Mechanical Model of the Atom
• Louis de Broglie (1892–1987) hypothesized that ________________, including
electrons, could also have ________________ behaviors.
• The figure illustrates that electrons orbit the nucleus only in ________________ ________________ wavelengths.
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The de Broglie equation predicts that all moving particles have wave
characteristics.
 represents wavelength.
h is Planck's constant.
m represents mass of the particle.
 represents velocity.
Example Problem de Broglie’s Equation Compare the wavelength for an electron (mass 9.11
x 10-31 kg) traveling at a speed of 1.0 x 107 m/s with that for a ball (mass = 0.10 kg)
traveling at 35 m/s.
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Honors Chemistry
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Chapter 5 Electrons in Atoms
Notes Outline
Heisenberg showed it is impossible to take any ________________ of an object
without ________________ it.
The ________________ ________________ ________________ states that it
is fundamentally impossible to know precisely both the velocity and position of a
particle at the same time.
The only quantity that can be known is the ________________ for an electron to
occupy a certain region around the nucleus.
________________ treated electrons as waves in a model called the quantum
mechanical model of the atom.
Schrödinger’s equation applied ________________ ________________ to
elements other than hydrogen.
The wave function predicts a three-dimensional region around the nucleus called the
________________ ________________.
Hydrogen Atomic Orbitals
• ________________ ________________ ________________ (n) indicates the
relative size and energy of atomic orbitals.
• n specifies the atom’s major energy levels, called the ________________ energy
levels.
• _____________ _____________ are contained within the principle energy levels.
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Each energy sublevel relates to orbitals of different ________________.
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
5.3 Electron Configuration
Objectives
• Apply the Pauli exclusion principle, the aufbau principle, and Hund's rule to write
electron configurations using orbital diagrams and electron configuration notation.
• Define valence electrons, and draw electron-dot structures representing an atom's
valence electrons.
Main Idea: A set of three rules determines the ________________ in an atom.
Ground State Electron Configuration
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The arrangement of electrons in the atom is called the ________________
________________.
The ________________ ________________ states that each electron occupies
the lowest energy orbital available.
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
The ________________ ________________ ________________ states that a
maximum of two electrons can occupy a single orbital, but only if the electrons have
opposite spins.
________________ ________________ states that single electrons with the
same spin must occupy each equal-energy orbital before additional electrons with
opposite spins can occupy the same energy level orbitals.
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Electron Configurations and Orbital Diagrams for Elements 1-10
Element
Atomic #
Electron Configuration
Orbital Diagram
H
He
Li
Be
B
C
N
O
F
Ne
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
________________ ________________ ________________ uses noble gas
symbols in brackets to shorten inner electron configurations of other elements.
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Electron Configurations for Elements 11-18
Element
Atomic #
Electron Configuration
Orbital Diagram
Na
Mg
Al
Si
P
S
Cl
Ar
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The electron configurations (for ________________, ________________, and
several other elements) reflect the increased stability of half-filled and filled sets
of s and d orbitals.
Exceptions to the Rule
Element
Atomic #
Electron Configuration
Orbital Diagram
Cr
Cu
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
Practice Problems #21-25 page 160
21. Write the ground-state electron configurations for the following elements.
a. Bromine (Br)
b. Strontium (Sr)
c. Antimony (Sb)
d. Rhenium (Re)
e. Terbium (Tb)
f. Titanium (Ti)
22. A chlorine atom in its ground state has a total of seven electrons in orbitals related
to the atom’s third energy level,
a. How many of the seven electrons occupy p orbitals?
b. How many of the 17 electrons in a chlorine atom occupy p orbitals?
23. When a sulfur atom reacts with other atoms. Electrons in orbitals related to the
atom’s third energy level are involved. How many such electrons does sulfur have?
24. An element has the ground-state electron configuration [Kr]5s24d105p1. It is part of
some semiconductors and used in various alloys. What element is it?
25. Challenge In its ground state, an atom of an element has two electrons in all orbitals
related to the atom’s highest energy level for which n = 6. Using noble-gas notation,
write the electron configuration for this element, and identify the element.
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
Valence Electrons
• ________________ ________________ are defined as electrons in the atom’s
outermost orbitals—those associated with the atom’s highest principal energy level.
• ________________________________ consists of the element’s symbol
representing the nucleus, surrounded by dots representing the element’s valence
electrons.
Electron Configurations and Dot Structures
Element
Atomic #
Electron Configuration
Electron Dot Structre
Li
Be
C
N
O
F
Ne
He
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Honors Chemistry
Chapter 5 Electrons in Atoms
Notes Outline
Practice Problems #29-33 page
29. Draw the electron-dot structure for the following elements.
a. Magnesium
b. Thallium
c. Xenon
30. An atom of an element has a total of 13 electrons. What is the element, and how
many electrons are shown in the electron-dot structure?
31. Challenge This element exists in the solid state at room temperature and at normal
atmospheric pressure and is found in emerald gemstones. It is known to be one of
the following elements: carbon, germanium, sulfur, cesium, beryllium, or argon.
Identify the element based on the electron-dot structure shown.
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Complete Mastering Problems #84-93 pages 167-168
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